It has been estimated that approximately 400,000 deaths each year in the United States are attributable to cancer. It appears that there is no single determinant of cancer cell growth and metastasis. Rather, the propensity of cancer cells to proliferate and metastasize is the sum total of numerous cellular characteristics, and individual cancer cells may use different mechanisms to achieve the same result [Weiss, Clinical and Experimental Metastasis, 7:127-167 (1989)].
While therapeutic strategies such as surgery, chemotherapy, and radiation therapy have improved in recent years [See, e.g., Krakoff, CA-A Cancer Journal for Clinicians, 41:264-278 (1991)], a substantial number of cancers are resistant to therapy and ultimately cause the death of the patient. Thus, a need emerges to discover new and useful means of cancer therapy.